Nice car! Very clean manifold.

1) The dimly lit warning lights is usually a failed brush set in the Bosch alternators' voltage regulators. That means it's running probably entirely on battery power :( I would look into it quickly. It stranded me once.

2) If you want to remove visible deposits like that and don't have the time and knowhow to do it, you might do the "chinese water torture" and seafoam treatment. I used it on two cars - my 84 244 with noticeable improvement and soot coming out the tailpipe, and my 90 744 with absolutely no noticeable results.

Might be worth a shot. And Good on ya for replacing the fuel line. I would suggest replacing them all if some of them are visibly failed. It's hard to know what you can't see.

Good Luck!